Induction heater



E- F. CASWELL INDUCTION HEATER Oct. 3, 1950 2 Sheets-Sheet 1 Filed Aug.30, 1948 INVENTOR.

EDGAR F. CASWELL ATTORNEYS 5- F. CASWELL INDUCTION HEATER Oct. 3, 1950Filed Aug. 30,1948

2 Sheets-Sheet 2 5 Hum INVENTOR. EDGAR F. CASWELL ATTORN EYS PatentedOct. 3, 1950 INDUCTION HEATER .Edgar F. Caswell, Detroit, Mich.,assignor to Kelsey-Hayes Wheel Company, Detroit, Mich., a corporation ofDelaware Application August 30, 1948, Serial No. 46,892

Claims.

The invention relates to induction heaters and refers more particularlyto induction heaters for articles having annular flanges and backs withthe latter provided with openings.

The invention has for one of its objects to provide an improvedinduction heater employing means for centering and moving the article tooperative position with its annular flange extending within an annularelectrical conducting element and separate means for moving a magneticflux conducting field element to operative position within the annularflange, the two means being subject to fluid under the same pressure andthe construction being such that the article is moved prior to the fieldelement.

The invention has for another object to so construct the inductionheater that the ratio of the resistance to movement of the articlemoving means to the resistance to movement of the field element movingmeans is less than the fluid pressure area of the article moving meansto the fluid pressure area of the field moving means to secure thedesired sequence of movement of the article and the field element.

With these and other objects in view, the invention resides in the novelfeatures of construction and combinations and arrangements of parts asmore fully hereinafter set forth.

In the drawings:

Figure 1 is a vertical section through an induction heater embodying theinvention;

Figure 2 is a top plan view thereof partly broken away.

As illustrated in the present instance, the in duction heater isdesigned for use with a brake drum shell having the annular flange I andthe back 2 provided with the central hub receiving opening 3. The heaterhas the base 4 and the head 5 above and supported on the base by therods 6. The head carries the annular upper mag netic flux conductingfield element 1 and the annular low frequency electrical conductingelement or winding 8. The field element is formed of the radiallyextending sections 9 below and secured to the head by suitable meanssuch as the angle irons Ill and I I welded to both the head andsections. Each section has the vertical portion I2 and the horizontalradially inwardly extending portion IS. The winding 8 is located withinthe vertical portions I2 and below the horizontal portions I3 and is ofa size to encircle the annular flange I when the shell is raised tooperative position. The winding is held in place by suitable means suchas the plates I4 engaged by the nuts l5 threaded .on the rods I6. The

plates are sleeved on the rods and the rods are located between thesections 9 and threaded in the head 5. The parts of the lower surfacesof the horizontal portions I3 radially inwardly of the winding arepreferably shaped to substantially fit the upper or outer side of theback 2 of the shell when the latter is in its operative position.

The induction heater also has the annular lower magnetic flux conductingfield element IFI adapted to be raised to operative position tocooperate with the field element 1 and the back 2 of the shell toconduct the lines of flux induced by electric current flowing throughthe winding around the annular flange I of the shell to thereby heat thelatter. The field element I1 is formed of the radially extendingsections I8, each of which is in vertical alignment with a section 9 ofthe upper field element and has the vertical portion IQ of a size toextend within the annular flange I of the shell and the horizontalradially outwardly extending portion 20 which in the operative positionof the field element I 1 extends closely adjacent to the lower end ofthe vertical portion l2 of the section 9 above the section I8. Thevertical portion l9 preferably has its upper face shaped tosubstantially fit the lower or inner face of the back 2 of the shell andthis upper face is preferably engageable with the back to clamp the sameagainst the portion I3 of the upper section above the lower section. Thesections I8 are mounted on the'table 2I and secured to the table byangle irons in the same manner as the sections 9 are secured to the head5. The table is supported upon the combined piston and cylinder 22 whichis vertically reciprocable within the vertical cylinder 23 mounted onthe bottom plate "24 fixedly secured upon the base 4.

The brake drum shell is supported when in in operative position upon therods 25 which extend upwardly between adjacent sections I8 of the fieldelement I l. The upper end of each of these rods is preferably cut awayto form the supporting face 26 for the annular flange of the shell andthe guide 21 engageable with the radially outer face of the annularflange. The rods are mounted on the plate 28 which is secured to theupper end of the cylinder .23 by means of the rods :29 which at theirlower ends threadedly engage the bottom plate 24.

For centering the brake drum shell relative to the winding 8 and alsoraising the brake drum shell to operative position, there is the pilot30 having the frusto-conical portion 3| engageable with the edge of theopening 3 in the back of the shell and also having the support portion32 engageable with the under or inner side of the back 2 of the shell.This pilot is carried by the piston 33 which is vertically reciprocablewithin the combined piston and cylinder 22 and is adapt ed to firstcenter the shell and then raise the same with its back against theradial portions of the sections of the upper field element and with itsannular flange within the winding.

The combined piston and cylinder 22 is slidably guided at the upper endof the cylinder 23 and is provided at its lower end with suitablesealing means 34 slidably engageable with the cylinder. The piston 33 isslidably guided at the upper end of the combined piston and cylinder 22and is provided at its lower end with suitable sealing means 35 slidablyengaging the combined piston and cylinder.

The bottom plate 24 forming the lower end of the cylinder 23 is providedwith the port 35 for the passage of fluid under pressure such ascompressed air into and from the lower end of the clylinder 23 bothradially inside and radially outside the combined piston and cylinder22. The lower faces of the combined piston and cylinder 22 and thepiston 33 are simultaneously subject to this fluid under pressure.

For the purpose of centering the brake drum shell and raising it tooperative position prior to raising the lower field element to operativeposition, the ratio of the resistance to movement of the piston 33 tothe resistance to movement of the combined piston and cylinder 22 isless than the ratio of the area of the piston to the area of thecombined piston and cylinder, so that when fluid imder pressure isadmitted to the lower end of the cylinder 23 the piston is raised to itsfull extent before the combined piston and cylinder is raised. Theresistance to movement of the piston 33 is the result of the combinedweights of the brake drum shell, the pilot 3? and the piston 33 plus thefriction between the piston 33 and the combined piston and cylinder 22.The resistance to movement of the combined piston and cylinder is theresult of the combined weights of the lower field element H, thecombined piston and cylinder 22 and the intermediate parts including thetable 2| plus the friction between the combined piston and cylinder 22,the piston 33 and the cylinder 23. Another manner of stating the ratiobetween the parts to secure the desired operation is that the pressureof the fluid entering the cylinder 23 on the area of the piston 33 minusthe resistance to movement or the piston 33 is greater than the pressureof the fluid entering the cylinder 23 on the area of the combined pistonand cylinder 22 minus the resistance to movement of the combined pistonand cylinder 22.

From the above description, it will be seen that I have provided aconstruction of low frequency induction heater in which the articlehaving the annular flange to be heated is first raised to operativeposition after which the lower field element of the heater is raised tooperative position and in which the means for effecting the raising ofthe article and the lower field element are separate but subject tofluid under the same pressure and the resistances to movement of thesemeans and their fluid pressure areas are such that the desired sequenceis secured.

What I claim as my invention is:

1. An induction heater for an article having an annular flange and aback provided with an opening, comprising an annular electricalconducting element of a size to encircle the annular flange, an annularmagnetic flux conducting field element adjacent said electricalconducting element, a piston having a pilot engageable with the edge ofthe opening in the back, said piston being movable to operative positionfor positioning the article with reference to said electrical conductingelement and for also positioning the article with its annular flangeextending within said electrical conducting ele ment, a second annularmagnetic flux conducting field element of a size to extend within theannular flange and shaped to cooperate in operative position with saidfirst mentioned field element to conduct lines of magnetic flux inducedby said electrical conducting element around the annular flange, and acombined piston and cylinder for moving said second mentioned fieldelement to operative position, said piston and said combined piston andcylinder having areas subject to fluid under the same pressure and theratio of the resistance to movement of said piston and the article tothe resistance to movement of said second field element and saidcombined piston and cylinder being less than the ratio of the fluidpressure area of said piston to the fluid pressure area of said combinedpisto n and cylinder whereby said piston is moved prior to movement ofsaid combined piston and cylinder.

2. In an induction heater for an article having an annular flange and aback provided with an opening, an annular electrical conducting elementof a size to encircle the annular flange, a pilot engageable with theedge of the opening in the back to center the article and alsoengageable with the back to carry the article, said pilot being movableto operative position to locate the article with its annular flangeextending within the electrical conducting element, a magnetic fluxconducting field element of a size to extend within the annular flange,a member carrying said pilot and a member carrying said field element,said members having areas subject to fluid under the same pressure andthe resistances to movement of said members and their areas being suchthat the area of said first mentioned member multiplied by the pressureof the fluid minus the resistance to movement of said first mentionedmember is greater than the area of said second mentioned membermultiplied by the pressure of the fluid minus the resistance to movementof said second mentioned member whereby said first mentioned member ismovable prior to movement of said second mentioned member.

3. An induction heater for an article having an annular flange and aback provided with an opening, comprising an annular electricalconducting element of a size to encircle the annular flange, an annularmagnetic flux conducting field element adjacent said electricalconducting element, a pilot engageable with the edge of the opening inthe back, a second annular magnetic flux conducting field element, meansfor moving said pilot towards said first mentioned field element toposition the article with its annular flange extending within theelectrical conducting element, and other means for moving said secondmentioned field element to extend within the annular flange and tocooperate with said first mentioned field element to conduct lines offlux around the annular flange, both of said means being operable byfluid under the same pressure and the ratio of the resistance tomovement of said first mentioned means to the resistance to movement ofsaid second means being less than the ratio of the fluid pressure areaof said first mentioned means to the fluid pressure area of said secondmentioned means whereby said first mentioned means is moved prior tosaid second mentioned means.

4. An induction heater for a brake drum shell having an annular flangeand a back provided with a central opening, comprising an annularelectrical conducting element of a size to encircle the annular flange,an annular magnetic flux conducting field element adjacent saidelectrical conducting element, a pilot engageable with the edge of thecentral opening in the shell back, an annular magnetic flux conductingfield element, means for moving said pilot toward said first mentionedfield element to position the shell with its annular flange extendingwithin said electrical conducting element and other means for movingsaid second mentioned field element to operative position cooperablewith said first mentioned field element to conduct lines of flux aroundthe annular flange of the shell, said pilot moving means and said secondmentioned field element moving means comprising concentric membersoperable by fluid under the same pressure.

5. An induction heater for an article having an annular flange and aback provided with a central opening, comprising a horizontal electricalconducting winding of a size to encircle the annular flange, an annularmagnetic flux conducting field element having a portion encircling saidwinding and a generally radially inwardly extending portion forengagement with the back, a vertical cylinder below said winding havinga port at its lower end for the passage of fluid under pressure, asecond annular magnetic flux conducting field element having a port on.o a i e o ext d it in the nn l r fl g and a second generally radiallyoutwardly extending portion, said portions of said second field elementin its operative position being cooperable with said portions of saidfirst mentioned field element to conduct lines of magnetic flux aroundthe annular flange, a combined piston and cylinder verticallyreciprocable within said cylinder and carrying said second fieldelement, a pilot engageable with the edge of the opening in the back tocenter the article and also engageable with the back to carry thearticle and a piston vertically reciprocable within said combined pistonand cylinder and carrying said pilot, said combined piston and cylinderand said piston having areas subject to the fluid under pressureentering through the port of said cylinder, and the ratio of theresistance to movement of the article, said pilot and said piston to therelative resistance to movement of said second field element and saidcombined piston and cylinder being less than the ratio of the area ofsaid piston to the area of said combined piston and cylinder whereby thearticle is centered and raised against said first mentioned fieldelement prior to raising of said second field element to operativeposition.

EDGAR F. CASWELL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,188,569 Endsley Jan. 30, 19402,280,064 Denneen et a1 Apr. 21, 1942 2,282,322 Denneen et al May 12,1942 2,288,034 Somes June 30, 1942 2,402,509 Strickland June 18, 19462,424,816 Groven et al, our July 29, 1 947

